1. Field of the Invention
The present invention relates to apparatuses and methods for processing signals, and more particularly, the invention relates to apparatuses and methods for processing signals having structures simplified by superimposing controlling signals on electric power signals transmitted via rotary transformers.
2. Description of the Related Art
In conventional video tape recorders (VTR), recording tracks are made narrower and wavelengths of the records are shortened to improve recording densities. In addition, in order to increase a data transmission rate of digital recording, the frequency of a reproducing signal needs to be higher. However, in the above cases, since an output from a reproducing head decreases, influence of noises from the outside thereby increases, with the result that the signal-to-noise ratio (S/N) of the reproducing-signal output decreases.
There are provided methods for solving the above problems. For example, an amplifier is disposed inside a rotary drum, and the amplifier and a reproducing head are connected in such a manner that they are disposed close to each other so as to reduce influence of the noises from the outside. In addition, a high-output reproducing head such as a Magneto-Resistive (MR) head is adopted to prevent the problems described above.
In these methods, however, since a bias current for the MR head or a power supply of the amplifier is required, electric power needs to be supplied to the rotary drum in some way.
Thus, an electric-power supplying method using a slip-ring, as shown in FIG. 1, is known. In this figure, a rotary drum 2 as a rotary unit rotates on a fixed drum 1 as a static unit. Electric power generated at the static unit is supplied to an amplifier or an MR head in the rotary unit, both of which are not shown in the figure, via a slip-ring 4. The slip-ring 4 is in contact with brushes 5. An insulating ring 6, as shown in FIG. 2, allows each of the brushes 5 to be insulated. A magnetic head 3 of the rotary drum 2 records a signal on a tape, which is not shown in the figure, or reproduces the signal recorded thereon.
As another electric-power supplying method, there is known a method in which an electric-power supplying winding is disposed in a rotary transformer 11 as shown in FIG. 3. The rotary transformer 11 is constituted of a power transmission channel 12, short-rings 13, recording channels 14-1 and 14-2, and reproduction channels 15-1 and 15-2. With a magnetic field generated in the winding disposed in grooves, signal transmission/reception is performed in each recording channels 14-1 and 14-2, and reproduction channels 15-1 and 15-2. In this arrangement, as shown in FIG. 3, the two recording channels 14-1 and 14-2, and the two reproduction channels 15-1 and 15-2 are disposed. The short-rings 13 are disposed to suppress crosstalk occurring between the power transmission channel 12 and the signal transmission channels including the recording channels 14-1 and 14-2 and the reproduction channels 15-1 and 15-2.
In order to sufficiently suppress the aforementioned crosstalk, since the double short-rings 13 are disposed, the size of the rotary transformer is increased. Thus, as shown in FIG. 4, there is also known a rotary transformer 11 in which a single short-ring is provided.
In terms of electric-power supply performed for a VTR, the structure of the example shown in FIG. 1 is complicated, production cost and the size of the apparatus are increased.
In the example shown in FIG. 3, since there are many grooves, the size of the rotary transformer is increased.
Furthermore, in the example shown in FIG. 4, since only a single groove is used for the short-ring, crosstalk occurring between the power transmission channel 12 and the signal transmission channels cannot be sufficient suppressed.
Therefore, in any of the above conventional methods provided in FIGS. 1 to 4, it is impossible to sufficiently suppress the above-mentioned crosstalk while the size of the apparatus is maintained small.
Accordingly, it is an object of the present invention to provide an apparatus and a method for processing signals, in which a control signal is superimposed on an electric power signal transmitted to a rotary transformer so as to reduce the size of the rotary transformer while crosstalk between a power transmission channel and signal transmission channels can be sufficiently suppressed.
To this end, according to an aspect of the present invention, there is provided a signal processing apparatus including a static unit, a rotary unit rotating in relation to the static unit, a rotary transformer, via which signal reception/transmission is performed between the static unit and the rotary unit, a unit for generating an electric power signal supplied to a circuit inside the rotary unit from the static unit, a unit for superimposing a control signal controlling the circuit inside the rotary unit on the electric power signal generated by the generating unit, a unit for supplying electric power to the circuit inside the rotary unit by detecting the electric power signal from the signal supplied to the rotary unit via the rotary transformer; and a unit for controlling the circuit inside the rotary unit by detecting the control signal from the signal supplied to the rotary unit via the rotary transformer.
Furthermore, according to another aspect of the present invention, there is provided a signal processing method using a signal processing apparatus in which signal reception/transmission is performed between a static unit and a rotary unit rotating in relation to the static unit via a rotary transformer. The signal processing method includes the steps of (1) generating an electric power signal supplied to a circuit inside a rotary unit from a static unit, (2) superimposing a control signal for controlling the circuit inside the rotary unit from the static unit on the electric power signal generated by the generating step, (3) supplying electric power to the circuit inside the rotary unit by detecting the electric power signal from the signal supplied to the rotary unit via a rotary transformer, and (4) controlling the circuit inside the rotary unit by detecting the control signal from the signal supplied to the rotary unit via the rotary transformer.
In the above-described apparatus and method, the control signal is superimposed on the electric power signal.